The antioxidant properties of phenolic compounds from olive pulp (PCO) of chamlal variety and those of individual phenolic compounds were evaluated and compared with that of vitamin C (Vit C). The antioxidant activity was measured by the tests of iron reduction and scavenging hydrogen peroxide (H2O2). Results showed that all the substances tested exhibit a reducing power. The PCO present activities of iron reduction and H2O2 scavenging higher than those of Vit C. The protective effect of PCO against oxidation of lipids and proteins from erythrocyte membranes was studied. The measurement of malondialdehyde generated under oxidative stress conditions induced by hydroxyl radicals generating system revealed that PCO have the most significant protective activity against lipid peroxidation (IC50 = 49.27 +/- 1.91 mu g mL(-1)). Paradoxically, Vit C revealed a pro-oxidant effect. Proteins oxidation was evaluated using the H2O2/FeSO4 system and electrophoresis. In the presence of PCO at 1 mg mL(-1), proteins of erythrocyte membranes were protected contrary to those treated with Vit C at the same concentration.